Sailing Plan is the basic information to estimate ship's position, and it should be sent at the time when a ship participates in this system. Reports should therefore be made when the ship departs from a port within the service area or when the ship enters the area.

Position Report is the information to verify if ship's position input according to the Sailing Plan in correct. The 1st report should therefore be sent at an optional time within 24 hours of departure from a port or entering the service area, and then the reports should be sent subsequently no less frequently than every 24 hours until Final Report.

Deviation Report is the information to be used for necessary correction of pre-reported Sailing Plan when a ship deviates from the intended course due to change in Sailing Plan. Reports should be sent whenever the Ship's position deviates 25 miles or more from the original track, or the port of destination is changed, or other changes occur with resultant change in Sailing Plan.